Various forms of containers, fabricated of paper board or other similarly flexible material, have been suggested heretofore. Such containers, boxes, or packages have, in accordance with one approach taken by the prior art, been fabricated by die cutting a roll of previously printed material, and by thereafter bending various portions of the die-cut configuration relative to one another to form the bottom, sides, and top of a box-like structure, the edges of which are secured to one another by glued seams.
This approach to box manufacture has a number of disadvantages. Since the box or container is formed, in its entirety, by bending portions of a unitary die-cut configuration relative to one another, all portions of the box are fabricated of the same basis weight of paper stock, and it is not possible, in this manufacturing technique, to use different basis weights of paper to form side and end flaps of the box respectively. In addition, since all portions of the box are formed by bending unitary portions of a die-cut panel relative to one another, the actual formation of the box tends to become comparatively time consuming, thereby increasing the cost of the box or container relative to its contents.
In an effort to obviate some of the foregoing difficulties, it has been suggested that packages be fabricated by passing roll stock through a printing unit operative to produce the desired logo, trademarks, etc., on said stock, with the material so printed then being slit into widths of appropriate dimension, and thereafter cut to desired lengths to form the individual sides, and bottoms, of a container structure of predetermined size. Such roll stock material can be driven through an automatic box forming machine by a sprocket mechanism which engages indexing holes formed along one edge of each strip; and the said indexing holes also provide a mechanism for effectively measuring the length of strip material being transported through the machine, to permit the strip to be cut into desired lengths automatically.
When an arrangement of this type is employed, it becomes possible to use two or more paper weights in the same box, e.g., one, comparatively heavy, paper weight can be employed to form the wide or main panel of a box structure whereas a lesser weight paper can be employed to form comparatively narrow end panels, as well as the bottom and top of the box structure. In addition, the dimensions of the box sides and ends can be readily varied at will to permit the fabrication of containers of varying dimension; and much greater flexibility is achieved in respect to the printing of the various box panels since the printing on selected portions of the box can be changed as desired without requiring any change in the printed information appearing on other portions of the box.
In order to seam the various panels together, in an automatic box-forming machine of the type discussed above, it has been suggested heretofore that the edges of the panels be somehow interlocked through the agency of their respective indexing holes or edge perforations. The types of seam arrangements suggested heretofore have, however, tended to produce a comparatively weak seam since portions of each edge of the panels being joined have been removed to form their respective indexing holes. In addition, seams formed by such interengagement of indexing holes tend to exhibit gaps between the interlocked portions of adjacent panels, whereby the seam is not "insect proof". In order to avoid these disadvantages, it has therefore been suggested that the seams be encapsulated in plastic material, or that the edges of the panels be overlapped sufficiently to permit the formation of a continuous new seam therebetween; but these alternative approaches, adopted in an effort to increase the strength and insect-proofness of the seam, represent comparatively expensive undertakings which, in addition, require the provision of additional equipment, thereby tending to increase the cost of the box.
The present invention, recognizing these disadvantages of the prior art, is concerned with an improved seam structure characterized by novel arrays of perforations in the cooperating edges of a pair of panels, which perforations are capable of being used for the transport of panels through an automatic box-forming machine, and which perforations are so fabricated that the adjacent edges of two panels may be readily interlocked with one another to form a seam structure which is far stronger than has been possible heretofore, and which is completely insect-proof.